From b7e9b1a01b9bfdaa8487071ef8f13353bb1a76fa Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Sun, 12 Sep 2021 21:38:38 +0200
Subject: basic PWM works now

---
 table-fan/table-fan.c | 71 +++++++++++++++++++++++++++++----------------------
 1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/table-fan/table-fan.c b/table-fan/table-fan.c
index bb5fa29..2cf9a32 100644
--- a/table-fan/table-fan.c
+++ b/table-fan/table-fan.c
@@ -31,42 +31,47 @@
 #include "led.h"
 #include "usbio.h"
 
-/* #define PWM_VAL OCR1BL */
-
-/* void pwm_init(void) */
-/* { */
-/*   DDRB |= (1<<PB6); */
-/*   TCCR1B = 0; */
-/*   TCNT1 = 0; */
-/*   OCR1B = 0; */
-/*   TCCR1A = (1<<COM1B1) | (1<<WGM10); */
-/*   TCCR1B = (1<<WGM12) | (1<<CS10); */
-/* } */
-
-/* inline void pwm_set(uint8_t val) */
-/* { */
-/*   PWM_VAL = val; */
-/* } */
-
-/* inline void pwm_inc(void) */
-/* { */
-/*   if(PWM_VAL < 255) */
-/*     PWM_VAL++; */
-/* } */
-
-/* inline void pwm_dec(void) */
-/* { */
-/*   if(PWM_VAL > 0) */
-/*     PWM_VAL--; */
-/* } */
+#define PWM_VAL OCR4B
+#define PWM_MAX 160
+
+void pwm_init(void)
+{
+  DDRB |= (1<<PB6);
+  TCCR4B = 0; // make sure timer is stopped
+
+  TCCR4A = (1<<COM4B1) | (1<<PWM4B);
+  TCCR4D = (1<<WGM40);
+  TCNT4 = 0;
+  OCR4C = 160;
+
+  OCR4B = 80; // set duty cycle to 50:50
+  TCCR4B = (1<<CS41); // start timer
+}
+
+inline void pwm_set(uint8_t val)
+{
+  PWM_VAL = val;
+}
+
+inline void pwm_inc(void)
+{
+  if(PWM_VAL < PWM_MAX)
+    PWM_VAL++;
+}
+
+inline void pwm_dec(void)
+{
+  if(PWM_VAL > 0)
+    PWM_VAL--;
+}
 
 void handle_cmd(uint8_t cmd)
 {
   switch(cmd) {
   case '0': led_off(); printf("ok\r\n"); break;
   case '1': led_on(); printf("ok\r\n"); break;
-  /* case '+': pwm_inc(); printf("pwm = %d\r\n", PWM_VAL);  break; */
-  /* case '-': pwm_dec(); printf("pwm = %d\r\n", PWM_VAL); break; */
+  case '+': pwm_inc(); printf("pwm = %d\r\n", PWM_VAL);  break;
+  case '-': pwm_dec(); printf("pwm = %d\r\n", PWM_VAL); break;
   case 'r': reset2bootloader(); break;
   default: printf("error\r\n"); return;
   }
@@ -83,13 +88,17 @@ int main(void)
 
   led_init();
   usbio_init();
-      // pwm_init();
+  pwm_init();
   sei();
 
       // FAN tacho input (enable Pull-Up)
   DDRD &= ~(1<<PD4);
   PORTD |= (1<<PD4);
 
+      // rotary encoder
+  DDRB &= ~((1<<PB4) | (1<<PB5));
+  PORTB |= (1<<PB4) | (1<<PB5);
+
   led_on();
   for(;;) {
     int16_t BytesReceived = usbio_bytes_received();
-- 
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